Electrical connector

ABSTRACT

Apparatus for enabling the rapid and reliable connection and disconnection of plug type connectors and their low cost manufacture, including a nut member that indicates when a screw is fully tightened, frames that facilitate unplugging in a commonly practiced though officially unrecognized manner, and contact elements shaped for accurate location in the frames. The nut member has a thread-engaging lip initially angled to extend away from the other connector frame, so that as a screw from the other frame becomes fully tightened the lip deforms and thereby suddenly increases screw-tightening resistance that signals the repairman to stop turning the screw. The female frame of a connector set has end walls that are tapered to permit disconnection of the frames by tilting them away from one another without binding. The recesses in each frame that receive tiny contact elements, have inwardly extending flanges near the tops of the recesses, and each resilient contact element has a wide lower portion biased upwardly against the flanges and a narrower upper portion passing between and beyond the flanges.

United States Patent 1 Iversen [111 3,764,957 Oct. 9, 1973 ELECTRICALCONNECTOR Ralph T. Iversen, Granada Hills, Calif.

[22] Filed: Dec. 17, 1971 [21] Appl. No.: 209,323

[75] Inventor:

[52] US. Cl. 339/92 R, 85/36, 339/184 M, 339/217 S [51] Int. Cl. HOlr13/54, H0lr 13/64 [58] Field of Search 339/92 M, 176 R, 339/176' M, 217S, 184, 186; 85/36 [56] References Cited UNITED STATES PATENTS I3,617,985 11/1971 Kehl 339/92 M 2,383,211 8/1945 Plumb 85/36 2,567,8849/1951 Heath 85/36 3,657,682 4/1972 lverson 339/103 M 2,775,917 l/l957Ferguson 85/36 3,555,494 1/1971 Baumanis 339/217 S 3,601,751 8/1971Pauza 339/217 S 3,633,152 l/1972 Podmore 339/217 S 2,938,190 5/1960Krchbiel 339/176 M 2,669,702 2/1954 Klostermann 339/75 M 3,277,42610/1966 Klostermann 339/176 R Primary Examiner-Marvin A. ChampionAssistant Examiner-William F. Pate, lIl

Attorney-Samuel Lindenberg et al.

[5 7 ABSTRACT Apparatus for enabling the rapid and reliable connectionand disconnection of plug type connectors and their low costmanufacture, including a nut member that indicates when a screw is fullytightened, frames that facilitate unplugging in a commonly practicedthough officially unrecognized manner, and contact elements shaped foraccurate location in the frames. The nut member has a thread-engaginglip initially angled to extend away from the other connector frame, sothat as a screw from the other frame becomes fully tightened the lipdeforms and thereby suddenly increases screw-tightening resistance thatsignals the repairman to stop turning the screw. The female frame of aconnector set has end walls that are tapered to permit disconnection ofthe frames by tilting them away from one another without binding. Therecesses in each frame that receive tiny contact elements, have inwardlyextending flanges near the tops of the recesses, and each resilientcontact element has a wide lower portion biased upwardly against theflanges and a narrower upper portion passing between and beyond theflanges.

7 Claims, ll-Drawing Figures I ll M ELECTRICAL CONNECTOR BACKGROUND OFTHE INVENTION This invention relates to electrical connector apparatusOne type of plug connector commonly usedintelephone installations andother applications includes a male frame or plug that can be insertedinto a female frame or receptacle, so that contact elements of the twoframes touch one another. Screw and nut type fasteners are oftenutilized to securely hold the frames together. One problem that oftenarises in field installations is over-tightening of the screws whichdamages the nut. This occurs largely because small screws are utilizedwhich require only a small torque for tightening.

Another problem that often arises in field installations of connectorsis binding during unplugging of the connectors. It is often assumed thatthe connectors will be unplugged by pulling one of them straight outfrom the other. However, in practice field repairmen often separate theconnectors by tilting them apart, inasmuch as tilting provides greaterleverage for initially loosening the connectors from one another. Theends of the connectors generally bind during such tilting, so thatrepairmen often have to tilt them back and forth while pulling themapart, which leads to increased effort and annoyance particularly inawkward installation areas.

' Each electrical connector of a set generally includes a row ofrecesses and a row of electrically conductive contact elements of springmaterial that lie in the recesses and have portions extending a slightdistance therefrom. The contact elements must be bent to accuratelyfollow .a predetermined curve so that when one side bears against thebottom of the recess the other side extends a small but definitedistance out of the recess. However, it is difficult to bend such springelements to close tolerances, so that close control of their shapeinvolves substantial expense.

SUMMARY OF THE INVENTION In accordance with one embodiment of thepresent invention, an electrical connector assembly is provided which iseasy to assemble and disassemble in the field and which can bemanufactured at low cost. The assembly includes a plug and receptaclethat can be connected and then securely joined by screws extending fromone connector and engaged with a nut on the other connector. A sheetmetal nut member is utilized which has a thread-engaging lip extendingwith a directional component away from the other connector. As the screwbecomes fully tightened, the lip begins to be deformed, or coned over,and begins to extend with a directional component towards the otherconnector. The repairman can sense a sudden increase in resistance toscrew turning as such coning over begins, so that he can cease furthertightening. Even if further tightening occurs and the lip is fully conedover, it thereafter merely clicks on the threads when the screw isturned so the repairman can sense that no further tightening isrequired.

The connectors are constructed to allow disassembly of the plug from thereceptacle by tilting them apart. To permit this, the ends of thereceptacle walls are tapered so that they diverge, to provide clearancethat allows tilting of the plug without binding on the receptacle.However, when the plug is fully installed, there is only a smallclearance between its end walls and the nearest regions of thereceptacle end walls, to assure accurate location of the plug.

Each of the connectors has a row of recesses that hold resilient contactelements, the elements being formed to extend a small distance out ofthe recesses so they contact corresponding elements on the otherconnector. In order to more accurately locate the protruding contactelement portions, a pair of sidewardly extending flanges is formed inthe recesses. Each of the contact elements is provided with a wide lowerportion that lies in the recess below the flanges and that resil-'iently bears against the flanges, and is also provided with a narrowupper portion that extends between the flanges and a small distance outof the recess. The fact that the wide lower portion of the contactelement is held at a predetermined depth within the recess means thatthe protruding portion of the element is more accurately located indepth, and therefore largerdimensional tolerances can be utilized informing the contact element.

The novel features of the invention are set forth with particularity inthe appended claims. The invention will be best understood from thefollowing description when read in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially sectional sideelevation view of connector apparatus constructed in accordance with theinvention, the connectors thereof being shown separated and ready forinterconnection;

FIG. 2 is a perspective view of a nut member of the apparatus of FIG. 1;

FIG. 3 is an enlarged sectional side view of a portion of the apparatusof FIG. 1, showing a screw and nut member engaged;

FIG. 4 illustrates a portion of theapparatus of FIG. 3, but showing theconfiguration .of the nut member after overtightening of the screw;

FIG. 5 is a plan view of the connectorapparatus of FIG. 1, showing thefaces of both connectors thereof;

FIG. 6 is a sectional side view of the connector apparatus of FIG. 1,showing the manner in which the two connectors can be tilted apart;

FIG. 6a shows the particular taper of the invention which allows tiltingapart of the connectors;

FIG. 7 is a perspective view of a portion of a connector frame of theapparatus of FIG. 1;

FIG. 8 is a side view of the apparatus of FIG. 7;

FIG. 9 is a view of the apparatus of FIG. 8 in an assembledconfiguration; and

FIG. 10 is a view taken on the line 10-10 of FIG. 9.

DESCRIPTION-OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates a pair ofelectrical connector assemblies 10, 12, each including a frame l4, l6and a hood 18, 20. One of the frames 14, is a male frame of plug, whilethe other frame 16 is a female frame or r'ecepta cle that can receiveplug 14. When the plug 14 is inserted into the receptacle 16, rows ofcontact elements 22, on the two frames engage one another to establishelectrical contact between a group of wires 24 leading to the connectorassembly 10 with another group of wires 26 leading to the other assembly12.

After the two assemblies 10, 12 have been connected by inserting theplug into the receptacle, they are generally fastened together by theuse of machine screws 28, that threadably engage nut members 30. Itoften requires many turns of the screw 28 before it becomes fullytightened on the nut 30. In prior art installations, field repairmenoften could not determine when to stop tightening of the screws. Suchover tightening could damage the typical sheet metal nut so that itwould not hold the screw. In accordance with the present invention, thenut member 30 is formed so that it readily indicates to the repairmanwhen full tightening has been achieved, and so that it functions to holdthe screw even after over tightening.

As shown in FIG. 3, the nut member 30 that is installed on the connectorassembly 12, has a pair of tread-engaging lip portions 32, 34 thatextend with directional components away from the other connectorassembly'l0. When the screw 28 is being tightened, the lip portions 32,34 threadably engage the screw to advance it. As the screw 28 becomesfully tightened, so that its head 35 firmly engages a ledge 37 andcannot advance any further towards the nut member, it begins to pull outthe lip portion 32, 34. If such turning of the screw 28 continues for afew turns, then the lip portions 32, 34 will be coned over, or in otherwords, bent in a reverse direction until they have the configurationshown at 32a, 34a in FIG. 4 wherein they extend with directionalcomponents towards the other connector assembly. However, as such coningover begins, the resistance to further turning of the screw 28 sharplyrises. This signals the repairman that he has fully tightened the screwand should stop any further tightening. Accordingly, the repairmannormally will not over tighten the screw so as to cone over the lips ofthe nut member.

The nut member can be formed from sheet metal, and has a sheet-like baseportion 36 and two curved arms 38, 40 extending from the base portion.The base portion has a slot 42 of substantially constant width except atthe center which forms the two lips 32, 34. The regions on oppositesides of the slot 42 are bent out of the plane of the rest of thesheet-like base portion, to allow the lip portions to extend at therequired incline. Slits 44 are formed at opposite ends of the slot 42 tofacilitate such bending of the regions on opposite sides of the slot.The two arms 38, 40 extend from opposite sides of the base, convergingto locations aligned with the hole formed between the lip portions 32,34 and then diverging. As shown in FIG. 3, the arms 38, 40 can engagethe threaded shank portion of the screw to keep it oriented so that itthreadably engages the lips 32, 34. The arms 38, 40 have free endportions 43, 45 that are received in slots 46, 48 of the frame 16 toretain the nut member 30 in a recess of the frame.

The nut member 30 is readily installed in the frame 16 by inserting itthrough an opening 50 therein until the free ends 43, 45 of the armssnap into the slots 46, 48. The base portion 36 of the nut member isheld by an inner ledge formed by a wall 52 of the frame. The nut member30 is useful during many tightenings and loosenings of the screw. If arepairman should accidently over tighten the screw and thereby cone overthe lips to the positions of FIG. 4, the lips will still threadablyengage the screw to prevent its free withdrawal. As the repairmancontinues to rotate the screw 28, the lips 32a, 34a will repeatedly riseand fall on the threads of the screw, creating clicking sounds that therepairman can sense. Thus, even if the nut is over tightened, it canstill function, and can still inform the repairman when the screw isfully tightened so that he does not have to continue turning it.

It is often assumed that the plug 14 is removed from the receptacle 16by pulling the plug straight out without tilting it. However, inpractice the plugs are often tilted in the manner shown in FIG. 6relative to the receptacle during removal. Repairmen often utilize thismethod because they can obtain greater leverage in loosening the plugfrom the receptacle by tilting it. However, the length of theplug-receiving region in the receptacle is often made only slightlygreater than the length of the plug, in order to accurately locate thecontact elements. As a result, repairmen using prior art connectorsoften had to tilt the plug or receptacle first one way then the other,since the connectors would bind on one another after a more than a fewdegrees of relative tilting.

In accordance with the present invention, the receptacle 16 is formed sothat the length of the recess or receiving portion 60 graduallydecreases with depth, from a minimum length only slightly greater thanthe length L of the plug at the innermost part of the region 60, andincreasing to a substantially greater length. This is accomplished bytapering the end walls 62, 64 of the receptacle so that its innersurfaces diverge from one another at an angle A of more than severaldegrees. For a connector assembly where the length L of the plug is aplurality of times greater than the depth D, which is the typicalsituation, an angle A of divergence of the end walls of more than about15 can allow complete disassembly by a single tilting without binding atthe end walls. Of course the angle that is required depends upon thetolerances and the length-to-depth ratio of the plug. However, a draftgreater than the draft of less than a few degrees, that is, less thanabout three degrees, that may be utilized in injection molding merely topermit ejection from the mold, is generally required.

When the connectors are separated in the manner shown in FIG. 6, thereceptacle 16 can pivot about the point 66 while the opposite end wall62 moves completely away from the plug 14, without binding. The factthat both ends of the receptacle are tapered means that pivoting canoccur at the deepest position 66 rather than at a location such as apoint 68 near the outer face of the receptacle. This means that the endwall 64 is not shifted outwardly so as to abut a shroud 70 that istypically provided to surround the plug 14. It would be possible totaper the ends of the plug 14 instead of the walls of the recess, butthis could result in a requirement for greater tapering to preventbinding of the receptacle 16 with the shroud 70 on the plug.

FIGS. 7-10 illustrate the manner in which the contact elements 22 arereceived and held in one of the frames such as the plug frame 14. Theframe 14 has numerous recesses arranged in two rows on either side ofthe frame, each recess holding one contact element 22. The contactelements 22 are formed with troughshaped rearward portions 82 forreceiving and connecting to the bared ends of wires, and haveloop-shaped forward portions 84 which are designed to contact similarelements of the other connector frame. The loopshaped forward portionmay be considered as having an inner arm 86 that lies near the bottomwall 88 of a recess, and an outer arm'90 that protrudes past the wallsof the recess.

The two arms 86, 90 of the contact element 22, amy be considered to bejoined together at a forward location 92 where the loop has its sharpestcurve. The contact element 22 is constructed of a conductive materialwhich is highly resilient, so that the outer arm 90 can deflect inwardlyas it encounters another contact element on the other frame, to firmlypress against it. When the outer arm 90 is deflected inwardly, theelement is bent primarily at the sharpest curved region 92. In prior artconnector assemblies, relatively close tolerances had to be maintainedover the form of the loop portion 84 and itsorientation with respect tothe rearward portion 82 to assure that the inner arm 86 was initiallybearing against the bottom wall 88 of the recess and so that the outerarm 90 extended a small but definite distance above the side face 94 ofthe frame. The accurate bending of such spring elements is difficult toachieve, and therefore considerable effort and expense was required inthe forming of the contact elements.

In accordance with the present invention, the recesses 80 are formedwith side walls 96 that have flanges 98 that extend towards one anotherto form a constriction near the outer end of the recess. Furthermore,the loop portion 84 of each contact element 22 is formed so that theinner arm 86 lies beneath the flanges 98 and is biased against them,while the outer arm 90 extends in a curve between and out past theflanges 98 and the side 94 of the frame. This is accomplished by formingthe lower arm 86 with a width W (FIG. slightly smaller than the distancebetween the side walls 96 of the recess but greater than the width C ofthe constriction. The outer arm 90, however,'has a width which is lessthan the width C of the constriction, so that the arm 90 can passbetween the flanges 98. The loop portion 84 of the contact element isformed so that the inner arm 86must be bent in order to fit between thebottom wall 88 of the recess and the flanges 98. This assures that thesteps 100' formed at the intersection of the inner and outer arms bearagainst the bottom of the flanges 98. The outer arm 90 is formed withsufficient curvature so that part of it lies above the side face 94 ofthe frame. The fact that the steps 100 fix the location of the center ofthe loop portion, means'that the contact elements can be formed withsmaller dimensional tolerances, and still there is assurance that theouter arm 90 will protrude a small but definite distance past the sideface 94 of the frame.

The loop portion 84 of the contact element is constructed of a strip ofresilient conductive material which is initially of uniform width.However, notches are formed at the steps or ledges 100, and portions 102at the sides of the strip are bent over to reduce the width of the outerarm 90 so that it can passthrough the constriction betweenthe flanges ofthe recesses. Each contact element 22 can be installed in a recess 80 bymoving the element forwardly through the recess beneath a retainer wall104 that bridges the recesses. The element is moved forward until thefront end of the element abuts the front wall 106 of the recess. Inorder to prevent retraction of the contact element, it is provided witha tab 108, as shown in FIG. 9, which normally lies above the bottom ofthe retainer wall 104. As the element is slid forward duringinstallation, the tab 108 deflects downwardly under a ledge 110 on theretainer and the tab then springs up to lie in line with the ledge 110.The contact element 22 thereafter cannot be moved rearwardly out of therecess because the tab 108 will abut the ledge to prevent this.

Thus, the present invention provides connector apparatus that can bereliably installed, easily disconnected, and manufactured at low cost.Reliable fastening is facilitated by the use of a nut member withreversedeformable lips that initially extend away from the oppositeconnector but which can be bent to reverse their direction orinclination. The deformable lips provide a sudden increase in tighteningtorque that signals the repairman to stop tightening the screw, and evenwhen the lips have been deformed because of over tightening, theyprovide clicks after full tightening that signal the repairman that thescrew has been fully tightened. Disconnection of the connector assemblyin a tilting manner is facilitated by angling at least one end wall ofthe connector, and preferably by angling both endwalls of thereceptacle. This allows accurate location of the plug in the receptaclewhen it is fully installed, and yet allows disconnection by tilting oneend of the plug away from the receptacle. Manufacture of the connectorsis facilitated by utilizing flanges in the elementreceiving recesses ofeach connector frame,- and by utilizing contact elements with inner armstoo wide to pass by the flanges and outer arms that pass between theflanges and a small distance past the sidewalls on the frame.

Although particular embodiments of the invention have been described andillustrated herein, it'is recognized that modifications and variationsmay readily occur to those skilled in the art and, consequently, it isintended that the claims be interpreted'to cover such modifications andequivalents. What is claimed is:

1. Electrical connector apparatus comprising:

a pair of connector assemblies, each having electrical contact elementsthat engage contact elements of the other when the two assemblies areconnected, and each having screw-engaging means for enabling fasteningby a screw to the other assembly;

at least one of said screw-engaging means which is on a first of saidassemblies including a nut member having a thread-engaging lip portionextending with a directional component away from the other assembly andbeing deformable,-by rotation of said screw when it cannot advance anyfurther into said nut member, to a reverse orientation extending with adirectional component toward the other assembly;

said nut member including a sheet-like base portion with a slot thereinand with slits extending perpendicular to said slot and intersectingopposite ends of said slot, said slot being widened at a center portionthereof so it can closely surround a cylindrical screw shank,

the portion of said base on at least one side of said slot being bentout of the plane of the rest of the sheet portions to extend with adirectional component away from said second connector to form saidthread-engaging lip portion;

said first connector assembly having a wall with a screw-passing holetherein and said base portion of the nut member resting against the wallbut with the lip portion being unsupported by the edge of the hole, thehole being large enough so that a length of the lip portion at leasttwice the thickness of the lip portion extends into the hole to permitreverse lip deformation into the hole, whereby to permit permanent lipdeformation so that a workman can notice a sudden decrease in resistanceto tightening of the screw.

2. An electrical connector comprising:

a male frame having an elongated plug portion with a plurality ofcontact elements thereon; and

a female frame having an elongated receiving portion with a recess onlyslightly longer than said plug portion for closely receiving said plugportion, said female frame having a plurality of contact elements alongsaid recess for contacting said elements of said plug portion when it isreceived in said recess;

said plug portion and said recess of said receiving portion beingconstructed so that at least one of them is tapered to have aprogressively greater length at progressively greater distances from theportion that first engages the other frame when the frames are mated,said tapering being sufficient to allow one end of said plug portion tocompletely withdraw from said recess while the other end of said plugportion remains at substantially the deepest position to which it can bereceived in said recess.

3. The electrical connector described in claim 2 wherein:

said receiving portion has end walls whose inner surfaces each have adraft or more than 4. The electrical connector described in claim 2wherein:

said plug portion is substantially a block with a length at least aplurality of times greater than its depth, and having a substantiallyconstant length between its ends, and

said receiving portion has end walls defining said recess, that divergefrom each other at an included angle of at least 15.

5. An electrical connector comprising:

a frame with a plurality of recesses that have opposite side walls andflanges extending from the side walls to leave a constriction of apredetermined width; and

plurality of resilient and electrically conductive contact elements,each element having a region formed into a loop, an inner portion ofsaid region being wider than said constriction and lying deeper withinsaid recess than said constriction, and said inner portion having an endwhere it merges with an end of an outer portion of said region which isnarrower than said constriction, at least part of said outer portionlying within said constriction, said end of said inner portion beingbiased against said flange and said end of the outer portion lying inthe constriction whereby to more accurately locate said outer portion indepth.

6. An electrical connector comprising: a frame with a plurality ofrecesses that have opposite side walls and flanges extending from theside walls towards each other to leave an opening of a predeterminedwidth between them; and

a plurality of resilient, electrically conductive contact elements, eachhaving first and second arms joined at one end to form a loop, saidfirst arm being wider than said predetermined opening between saidflanges and lying deeper within said recess than said flanges and biasedagainst said flanges at a location beyond the beginning of the loop, andsaid second arm being narrower than said predetermined opening betweensaid flanges and protruding from it, whereby said second arm is moreaccurately located in depth.

7. The electrical connector described in claim 6 wherein:

said first arm is resiliently deformed between a bottom wall of therecess and the flange, and the depth of the flanges is less than thedepth of the recess between the bottom surfaces of the flanges and saidbottom wall.

1. Electrical connector apparatus comprising: a pair of connectorassemblies, each having electrical contact elements that engage contactelements of the other when the two assemblies are connected, and eachhaving screw-engaging means for enabling fastening by a screw to theother assembly; at least one of said screw-engaging means which is on afirst of said assemblies including a nut member having a thread-engaginglip portion extending with a directional component away from the otherassembly and being deformable, by rotation of said screw when it cannotadvance any further into said nut member, to a reverse orientationextending with a directional component toward the other assembly; saidnut member including a sheet-like base portion with a slot therein andwith slits extending perpendicular to said slot and intersectingopposite ends of said slot, said slot being widened at a center portionthereof so it can closely surround a cylindrical screw shank, theportion of said base on at least one side of said slot being bent out ofthe plane of the rest of the sheet portions to extend with a directionalcomponent away from said second connector to form said thread-engaginglip portion; said first connector assembly having a wall with ascrew-passing hole therein and said base portion of the nut memberresting against the wall but with the lip portion being unsupported bythe edge of the hole, the hole being large enough so that a length ofthe lip portion at least twice the thickness of the lip portion extendsinto the hole to permit reverse lip deformation into the hole, wherebyto permit permanent lip deformation so that a workman can notice asudden decrease in resistance to tightening of the screw.
 2. Anelectrical connector comprising: a male frame having an elongated plugportion with a plurality of contact elements thereon; and a female framehaving an elongated receiving portion with a recess only slightly longerthan said plug portion for closely receiving said plug portion, saidfemale frame having a plurality of contact elements along said recessfor contacting said elements of said plug portion when it is received insaid recess; said plug portion and said recess of said receiving portionbeing constructed so that at least one of them is tapered to have aprogressively greater length at progressively greater distances from theportion that first engages the other frame when the frames are mated,said tapering being sufficient to allow one end of said plug portion tocompletely withdraw from said recess while the other end of said plugportion remains at substantially the deepest position to which it can bereceived in said recess.
 3. The electrical connector described in claim2 wherein: said receiving portion has end walls whose inner surfaceseach have a draft or more than 15*.
 4. The electrical connectordescribed in claim 2 wherein: said plug portion is substantially a blockwith a length at least a plurality of times greater than its depth, andHaving a substantially constant length between its ends, and saidreceiving portion has end walls defining said recess, that diverge fromeach other at an included angle of at least 15*.
 5. An electricalconnector comprising: a frame with a plurality of recesses that haveopposite side walls and flanges extending from the side walls to leave aconstriction of a predetermined width; and a plurality of resilient andelectrically conductive contact elements, each element having a regionformed into a loop, an inner portion of said region being wider thansaid constriction and lying deeper within said recess than saidconstriction, and said inner portion having an end where it merges withan end of an outer portion of said region which is narrower than saidconstriction, at least part of said outer portion lying within saidconstriction, said end of said inner portion being biased against saidflange and said end of the outer portion lying in the constrictionwhereby to more accurately locate said outer portion in depth.
 6. Anelectrical connector comprising: a frame with a plurality of recessesthat have opposite side walls and flanges extending from the side wallstowards each other to leave an opening of a predetermined width betweenthem; and a plurality of resilient, electrically conductive contactelements, each having first and second arms joined at one end to form aloop, said first arm being wider than said predetermined opening betweensaid flanges and lying deeper within said recess than said flanges andbiased against said flanges at a location beyond the beginning of theloop, and said second arm being narrower than said predetermined openingbetween said flanges and protruding from it, whereby said second arm ismore accurately located in depth.
 7. The electrical connector describedin claim 6 wherein: said first arm is resiliently deformed between abottom wall of the recess and the flange, and the depth of the flangesis less than the depth of the recess between the bottom surfaces of theflanges and said bottom wall.